restful 與 form_for

不可以在 /news/new 的 view 裡面寫 form_for @news ~"~

 

operate existed tables in rails

Just need specify table name and primary key in Model. All attribution in tables will appear automatically.

class ModelName < ActiveRecord::Base
    self.table_name = "table_name"
    self.primary_key = "primary_key"
end

 

tree implement in ruby

Just for fun, but it work well.

 01 #!/usr/bin/env ruby
 02 # 
 03 # 
 04 
 05 
 06 def tree(dirname, indent = "  |")
 07     puts dirname + "/" if indent == "  |"
 08     dir = Dir.open dirname
 09     for f in dir
 10         if f == "." || f == ".."
 11             next
 12         elsif File.directory? dirname+"/"+f
 13             puts indent + "-" + f + "/"
 14             tree( dirname+"/"+f, indent+"  |")
 15         else
 16             puts indent + "-" + f
 17         end
 18     end
 19 end
 20 
 21 tree (ARGV[0]? ARGV[0] : ".")

 

closure tip

closure is so fun.
well design for meta programming.

note 1:

 01 #!/usr/bin/env ruby        
 02
 03 class Hash
 04     def find_all
 05         temp_hash = {}
 06         each {|key,value| temp_hash[key] = value if yield(key,value) }
 07         temp_hash
 08     end 
 09 end 
 10 
 11 square = { 0 => 0, 1 => 1, 2 => 4, 3 => 9 }
 12 
 13 new = square.find_all { |key,value| key > 1 }
 14 puts new.inspect

pass yield values.

note 2:

 01 #!/usr/bin/env ruby        
 02
 03 class Person
 04     attr_accessor :name
 05     def initialize(name)
 06         @name = name       
 07     end
 08 end
 09 
 10 def command(obj,method)    
 11     obj.each {|x| yield x.send(method)}
 12 end
 13 
 14 family = []
 15 
 16 %w(shelling sherry appollo).each do |name|
 17     family.push Person.new(name)    
 18 end
 19 
 20 command family, :name do |x|
 21     puts "hello, I am #{x}."
 22 end

Every object in array call the same function.

 
 

boring comparison

show complex data structure in perl and ruby

perl
#!/usr/bin/env perl
use warnings;
use Data::Dumper;

$a = ["a", "b", "c", { "key" => "value" } ];
print Dumper $a;

ruby
#!/usr/bin/env ruby
a = ["a", "b", "c", { "key" => "value" } ]
puts a.inspect
 
 

has_many() function note

if has_many :order
order.delete_all just set foreign key null
order.destroy_all clear all sub record
 
 

apache2 and mongrel cluster on debian

Enable apache2 proxy
$ sudo a2enmod proxy proxy_http proxy_balancer

Configure Proxy in a virtual host
/etc/apache2/site-enabled/default add
DocumentRoot "RailsApp/public"
    # even only RailsApp also work
ProxyPass / balancer://localhost/
ProxyPassReverse / balancer://localhost/
< proxy balancer://localhost/ >
    BalanceMember http://localhost:3000
    BalanceMember http://localhost:3001
    BalanceMember http://localhost:3002
< /proxy >

Then set mongrel cluster
$ sudo gem install mongrel_cluster
$ cd RailsApp
$ mongrel_rails cluster::configure -e development -p 3000 -N 3
    # write config/mongrel_cluster.yml
$ mongrel_rails cluster::start

Final, restart apache2 and it work.

 
 

rss feed in rails

Note for the Way to create Atom and RSS 2.0 feed.

$ ./script/generate controller feed

Suppose that the model we want show in feed is Post

class FeedController < ApplicationController
    def rss
        @rss = @@post
    end

    def atom
        @atom = @@post
    end

  private
    @@post = Post.find :all,
        :order => "update_at", :limit => 10
end

Then write the view.

app/view/feed/rss.rxml

01 xml.instruct! :xml, :version=>"1.0"
02 xml.rss(:version=>"2.0"){
03     xml.channel{
04         xml.title("The site title")
05         xml.link(url_for("/"))
06         xml.description("The site description")
07         xml.language('en-us')
08
09         @rss.each do |rss|
10         xml.item {
11             xml.title rss.title
12             xml.link ""
13             xml.description rss.content
14             xml.pubDate rss.update_at
15             xml.guid ""
16             xml.author rss.declarer
17         }
18         end
19     }
20 }


app/view/feed/atom.rxml

01 xml.instruct! :xml, :version=>"1.0"
02 xml.feed "xmlns" => "http://www.w3.org/2005/Atom" do
03     xml.title("The site title")
04     xml.link(url_for "/")
05     @atom.each do |atom|
06         xml.entry {
07             xml.title(atom.title)
08             xml.summary(atom.content)
09         }
10     end
11 end

app/view/layout/application.rhtml add

<%= auto_discovery_link_tag :rss, { :controller => '/rss', :action => 'rss' }, { :title => "RSS 2.0" } %>
<%= auto_discovery_link_tag :rss, { :controller => '/rss', :action => 'atom' }, { :title => "Atom" } %>

 
 

rails helper block

Write for memo.
To set a helper in the form

<% helper_name do %>
    <div>blah</div>
<% end %>.

The definition is

def helper_name(&block)
    content = capture(&block)
    concat("what we want write before block".block.binding)
    concat(content,block.binding)
    concat("what we want write after block",block.binding)
end

By the way, partial is the way do the same thing once. if the outer html is used frequently, the way to define a helper as above will be better.
 
 

spakit

The rails plugin spakit means Single Page Application KIT. It can transform rails app into single page app but not modify app structure in large scale by loading content of other controller into primary controller.

The installation step is from handlino.com
$ sudo gem install spakit
$ cd railsapp/vendor/plugins/
$ gem unpack spakit
$ mv spakit-version spakit
now installation finished.

Before using it, spakit need a layout railsapp/app/view/layout/spakit.rhtml<%= flash[:notice] %>
<%= yield %>
And the layout application.rhtml should contain
<%= javascript_include_tag :defaults %> to include default js file.

Now we can use it happy. Add <div id="content"></div> into the view of primary controller, and set a spakit link: <%= spakit_link_to 'new person', :url => new_person_path %>, the content of the url will appear in the div#content.

Also two other helpers contain in spakit, spakit_form_for and spakit_form_tag

link1: spakit at rubyforge
link2: spakit at github

annotate models

The plugin used for adding column annotate into model file is introduced in Ralls Bible. Write for note. the newer introduction at http://pragdave.pragprog.com/pragdave/2006/02/annotate_models.html. Just two step to use it.
1.script/plugin install http://repo.pragprog.com/svn/Public/plugins/annotate_models
2. rake annotate_models
And all model now with column annotate at file head.

the end of winter recess

這個寒假比預期的廢了很多，預定的事項，想讀的書，沒一件做完的，再來，三月一日就是研究所考試了，看著別人即將踏入考場，自己摸著鼻子甸甸自己剩下不到一年的時間儲備，真是難以說話。雖然沒有完成預定的事項，不過練習 perl/ruby 之餘還是寫了些 bot，cwbbot 是個簡單的 ruby 天氣預報機器人，提供他 twitter 的帳號和密碼，丟進 crontab，就可以每天自動取得明日溫度。

perl 和 ruby 的 twitter shell

twitter 最近紅透半邊天，perl 和 ruby 都有了 twitter api，現在還有 twitter shell，perl 的 twitter shell 利用 cpan 下 install Twitter::Shell 就可以得到 /usr/local/bin/twittershell， 使用方式為新增一個 yaml，如： touch ~/.twittershell.yml ， 裡面填入

username: yourtwitteraccount
password: yourtwitterpassword

在 shell 下 twittershell -c ~/.twittershell.yml 就進入該 shell， help 可以得到幫助。

ruby 版本內建在 twitter 這個 gem 內， sudo gem install twitter 就可以得到 /usr/bin/twitter，直接在 shell 下 twitter 就可以得到幫助。不過 ruby 版本對 unicode 沒有支援，無法顯示中文，嘗試在 twitter gem 內的 twitter.rb 加入

require 'jcode'
$KCODE = 'u'

，不過沒有效果，作者也表示暫時不會加入 unicode 支援。

land mine in file name extension of ruby

和 perl 不同, ruby 的 third party module package, 也就是 gems, 副檔名和一般 script 都一樣是 ".rb", ruby 搜尋 module 的 path 似乎又包含了 ".", 所以如果使用的 script 檔名和 script 引用的 gems 內的檔名相同的話, 就會衝突 :/

gem update on debian

日前升級了 debian 上的 gem，隨即發生無法使用的狀況，檢查之後發現，debian 內建的 rubygems 套件安裝位置在 /var/lib/gems/，而gem 原生的安裝位置在 /usr/lib/ruby/gems/，因此升級後會發生找不到正確 gems 的狀況。

因為 gems 的目錄配置方式不符合 FHS，debian 在 3.x 就一直遲遲不發佈 rubygems 套件，即使目前 4.x 發佈了，在目錄的相容性上問題也很多。

目前看來要安裝 gems 又不用通過官方安裝包條件的最好方法就是，先安裝內建的 rubygems，執行 gem update --system 之後，會得到一個 /usr/bin/gem1.8，然後移除 rubygems 和 libgems-ruby1.8，最後將 /usr/bin/gem1.8 重新命名成 /usr/bin/gem，就可以得到原生的 gem。

example ruby

今天在我的 Debian 上面裝了 ruby 來嚐鮮，感覺相當有趣，就如同作者所希望的 ruby 這顆紅寶石給人輕快簡單的感覺，相較於 perl 這個穩重的珍珠，各有所擅。

要建制一個 Rail application 的環境需要下的指令有

sudo aptitude install ruby ri rdoc irb rubygem

這還會自動安裝 libreadline 等等 lib
其中

• ri 可以用來查詢 module
• irb 是 interactive ruby
• rubygem 是 ruby 的 package management framework，安裝完後有 gem 指令可用
• rdoc 可以用來生成 doc

然後再下

sudo gem install rails --include-dependencies

就可安裝 Rails，不過還未包含 Mongrel 伺服器，等等再研究須不需要現在安裝